The integrated actions of dopaminergic neurons were investigated in striatum and N. accumbens after long term treatment with antischizophrenic drugs. Long term treatment with classical antischizophrenics produces tolerance to the activation of the DA striatal system. Tolerance is not observed after long term treatment with atypical antischizophrenics. In striatum, the supersensitivity of DA receptors produced by these drugs is associated with an increase in calcium binding protein (calmodulin). The calmodulin content was determined in striatum and frontal cortex of control subjects and in eleven schizophrenic patients. No differences were observed in the calmodulin content between these two groups.